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Influencia diferencial de la expresión de Slc7a11 y la condición corporal sobre la pigmentación producida por feomelanina en dos poblaciones de trepador azul Sitta europea con diferente riesgo de depredación

The expression of the gene Slc7a11 promotes the antioxidant capacity of cells by providing them with cysteine that can be used for the synthesis of glutathione (GSH), the most important intracellular antioxidant. In melanocytes, intracellular cysteine can also enter melanosomes and get incorporated in the pigment pheomelanin synthesis pathway, thus decreasing cysteine availability for GSH synthesis and potentially creating chronic oxidative stress. Therefore, this study hypothesized that a mechanism limiting the use of intramelanocytic cysteine for pheomelanin synthesis in environmental conditions generating oxidative stress may be physiologically advantageous and favored by natural selection. Evidence we searched of such a mechanism by comparing the influence of melanocytic Slc7a11 expression on pheomelanin?based pigmentation in developing Eurasian nuthatch Sitta europaea nestlings from two populations differing in predation risk, a natural source of oxidative stress. Pheomelanin synthesis and pigmentation tended to increase with Slc7a11 expression in the low?risk population as expected from the activity of this gene, but decreased with Slc7a11 expression in the high?risk population. The same was not observed in the expression of five other genes influencing pheomelanin synthesis without affecting cysteine availability in melanocytes. The influence of body condition on the intensity of pheomelanin?based pigmentation also differed between populations, being positive in the low?risk population and negative in the high?risk population. The resulting pigmentation of birds was more intense in the high?risk population. These findings suggest that birds perceiving high predation risk may limit the use of cysteine for pheomelanin synthesis, which becomes independent of Slc7a11 expression. Some birds may have thus evolved the ability to adjust their pigmentation phenotype to environmental stress. informacion[at]ebd.csic.es: Galván & Sanz (2020) Differential influence of Slc7a11 expression and body condition on pheomelanin-based pigmentation in two Eurasian nuthatch Sitta europaea populations with different predation risk. J Avian Biol DOI 10.1111/jav.02275


https://onlinelibrary.wiley.com/doi/10.1111/jav.02275
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Shorebirds disperse a wide variety of plants along the Atlantic flyway

Shorebirds disperse a wide variety of plants along the Atlantic flyway

Almost no empirical work has been done before on the plants dispersed by migratory shorebirds (Charadriiformes). By sampling faeces and regurgitated pellets in Doñana (Spain), England, Ireland and Iceland, scientists found intact seeds of 27 plant taxa, only four of which have a fleshy fruit widely considered diagnostic for this "endozoochory" dispersal process. Furthermore, 89% of the seeds were from terrestrial plants that are broadly distributed along the Atlantic flyway. Shorebirds are excellent vectors for long-distance dispersal (LDD), and seeds were carried by birds at the beginning or end of migratory flights between England and Iceland. This work suggests that seed morphology alone cannot predict LDD mechanisms, and that aquatic plants are not the only ones dispersed readily by shorebirds. Four alien species were dispersed, including the buttonweed Cotula coronopifolia which had a germination rate of 45% after gut passage, and is spreading quickly in coastal wetlands frequented by shorebirds. informacion[at]ebd.csic.es: Lovas-Kiss et al 2018. Shorebirds as important vectors for plant dispersal in Europe. Ecography doi: 10.1111/ecog.04065


https://onlinelibrary.wiley.com/doi/full/10.1111/ecog.04065